Effect of 650-nm Pulsed-Mode Diode Laser Irradiation Time on Fibroblast Proliferation and Odontoblast-Like Cell Counts

Abstract This article aims to analyze the effect of 650-nm pulsed-mode diode laser irradiation time on fibroblast proliferation and odontoblast-like cell counts in mechanically exposed pulp of Wistar rat molars. This laboratory experimental study used 48 healthy male Wistar rats. The subjects were divided into eight groups (1–8): control, 10-second irradiation, 20-second irradiation, and 40-second irradiation, with observation periods of 7 and 28 days. After pulp exposure of the maxillary first molar, the cavities were restored with resin-modified glass ionomer cement (RMGIC). The rats were sacrificed according to the designated observation period, and the specimens were processed for hematoxylin and eosin staining. Fibroblast and odontoblast-like cell counts were evaluated microscopically. Data distribution was analyzed using the Shapiro–Wilk test, followed by a homogeneity test, one-way analysis of variance (ANOVA), and Tukey's honestly significant difference (HSD) post hoc test with a significance level of 0.05. Significant differences were found in fibroblast and odontoblast-like cell counts among the treatment groups. The highest mean fibroblast count was observed in the 40-second irradiation group on day 28 (19.50 ± 2.59), while the highest mean odontoblast-like cell count was observed in the same group (18.50 ± 2.17). Overall, the 40-second irradiation group demonstrated greater fibroblast proliferation and higher odontoblast-like cell counts than the 10-second and 20-second irradiation groups. A 650-nm pulsed-mode diode laser was associated with increased fibroblast proliferation and higher odontoblast-like cell counts in Wistar rat pulp tissue. The 40-second irradiation time produced the greatest effect compared with 10- and 20-second irradiation.